Dozens of Texas drivers have been stopped at a police road block, where they were then directed into a parking lot and forced into surrendering blood, saliva and breath samples in a study that has upset civil liberties advocates.

The National Highway Traffic Safety Administration admitted it was attempting to conduct a government study meant to determine the number of drunk or drug-impaired drivers on the road at any given time.

“It just doesn’t seem right that you can be forced off the road when you’re not doing anything wrong,” Kim Cope, who said she was forced to the side of the road while making her way to lunch, told NBCDFW.com. “I gestured to the guy in front that I just wanted to go straight, but he wouldn’t let me and forced me into the parking spot.”

The tests were made even more mysterious when reporters, alerted to the situation by concerned drivers, were unable to find any officers in the Fort Worth Police Department who had been involved. The NHTSA only admitted its involvement after local media sought answers.

The department, which says its mission is to “save lives, prevent injuries, and reduce vehicle-related crashes,” maintains that participation in the research was completely voluntary. But Ms. Cope said she felt trapped during what seemed to be an investigation.

“I finally did the breathalyzer test just because I thought it would be the easiest way to leave,” she said. “It just doesn’t seem right that they should be able to do any of it. If it’s voluntary, it’s voluntary, and none of it felt voluntary.”

When pressed, the FWPD said it was “reviewing the actions of all police personnel involved to ensure that FWPD policies and procedures were followed.” The NBC affiliate was able to determine that the Pacific Institute for Research and Evaluation, a government contractor, was hired to conduct the check.

An NHTSA spokesperson admitted similar programs were being conducted in 30 other cities throughout the US.

But civil liberties attorney Frank Colosi does not accept the rationale.

“You can’t just be pulled over randomly or for no reason,” he said. “They’re essentially lying to you when they say it’s completely voluntary, because they’re testing you at that moment.”

He added that drivers who refused may have been targeted by police for inadvertently giving the impression they were operating a vehicle under the influence. He also told NBC that fine print on the form told drivers their breath was being tested by “passive alcohol sensor readings before the consent process has been completed.”

This oddity comes just months after Texas state troopers were caught on video conducting vaginal and cavity searches on female drivers at the side of the road. The videos quickly went viral, and attorneys for the women filed federal lawsuits against the troopers.

“It’s ridiculous,” Peter Schulte, a former Texas police officer and prosecutor, told the New York Daily News earlier this year. “I was a law enforcement officer for 16 years and I never saw anything like it.”